Geodesy is among the oldest branches of Earth science with historical record of geodesy study by Thales of Miletus more than 2000 years. Originally geodesy was defined as the science of measuring and portraying of the...Geodesy is among the oldest branches of Earth science with historical record of geodesy study by Thales of Miletus more than 2000 years. Originally geodesy was defined as the science of measuring and portraying of the Earth＇s surface, i.e., assuming that the Earth is展开更多
The study area is rich in shale gas resources and has reached the stage of comprehensive development. Shale gas extraction poses risks such as induced seismicity and well closure, compounded by the limited availabilit...The study area is rich in shale gas resources and has reached the stage of comprehensive development. Shale gas extraction poses risks such as induced seismicity and well closure, compounded by the limited availability of fi xed seismic monitoring stations nearby. To address these challenges, a dense observation array was developed within the study area to monitor and analyze microseismic activity during hydraulic fracturing. Microseismic events generated by hydraulic fracturing typically exhibit low amplitude and signal-to-noise ratio, rendering traditional manual analysis methods impractical. To overcome these limitations, an innovative artifi cial intelligence method combining picking-association-location (PAL) and match-expand- shift-stack (MESS) techniques (PALM) has been utilized for automated seismic detection. Numerous factors influence the accuracy of microseismic detection and localization. To evaluate these factors, the effects of various velocity structure models, instrument types, and station distributions on seismic location were analyzed and compared. The results indicate that the PALM method significantly mitigates the influence of velocity structure models on seismic location accuracy. Additionally, the use of broadband seismic instruments and a uniform station distribution enhances the precision of seismic location results. Furthermore, by integrating data from diff erent types of observation instruments, a comprehensive seismic catalog for the study area was established. These fi ndings not only enhance seismic location accuracy but also provide valuable guidance for optimizing regional seismic monitoring network design and improving seismic risk assessment.展开更多
On September 5, 2022, an earthquake of magnitude M_(S)6.8 occurred in Luding County, Sichuan Province.This earthquake occurred at the key part of the southeast-clockwise extrusion of material on the eastern margin of ...On September 5, 2022, an earthquake of magnitude M_(S)6.8 occurred in Luding County, Sichuan Province.This earthquake occurred at the key part of the southeast-clockwise extrusion of material on the eastern margin of the Qinghai Plateau, the Y-shaped confluence of the Xianshuihe, Longmenshan and Anninghe fault zones. In this study, the three-dimensional dynamic crustal density changes in the earthquake area are obtained by the typical gravity change data from 2019 to 2022 before the earthquake and gravity inversion by growing bodies. The results indicate that gravity changes presented an obvious fourquadrant and gradient belt distribution in the Luding area before the earthquake. The threedimensional density horizontal slices show that small density changes occurred at the epicenter in the mid-to-upper crust between 2019.9-2020.9 and 2019.9-2021.9. At the same time, the surrounding areas exhibited a positive and negative quadrant distribution. These observations indicate that the source region was likely in a stable locked state, with locking-in shear forces oriented in the NW and NE directions. From 2021.9 to 2022.8, the epicentral region showed negative density changes, indicating that the source region was in the expansion stage, approaching a near-seismic state. The three-dimensional density vertical slices reveal a southeastward migration of positive and negative densities near the epicenter and on the western of the Xianshuihe Fault Zone, indicating that the material is flowing out to the southeast. The observed local negative density changes at the epicenter along the Longmenshan Fault Zone are likely associated with the NE-oriented extensional stress shown by the seismic source mechanism. The above results can provide a basis for interpreting pre-earthquake gravity and density changes,thereby contributing to the advancement of earthquake precursor theory.展开更多
Coal mining predisposes soils to heavy metal(HM)accumulation,which adversely affects the ecological environment and human health,particularly in extremely arid and vulnerable areas.In this study,soil samples were gath...Coal mining predisposes soils to heavy metal(HM)accumulation,which adversely affects the ecological environment and human health,particularly in extremely arid and vulnerable areas.In this study,soil samples were gathered from the Black Mountain Open Pit Coal Mine in Turpan City,Northwest China to determine the health risk of heavy metals(HMs).Results showed that positive matrix factorization model divided the sources of soil HMs into four categories,i.e.,natural and animal husbandry(43.46%),industrial transportation(22.87%),fossil fuel combustion(10.64%),and atmospheric deposition and domestic pollution(23.03%).All kinds of pollution evaluation indices showed that Cd(cadmium)and Pb(plumbum)pollution was evident.The Monte Carlo simulated health risk assessment results showed that 4.00%non-carcinogenic risk and 12.00%carcinogenic risk were posed to children,and the positive matrix factorization-based health risk assessment showed that fossil fuel combustion had the highest contribution to the health risks to adults and children,while industrial transportation was the lowest.In this study,the risks of HMs in the soil of mining area were analyzed using source analysis,which not only provides reliable data support for the prevention and control of HM pollution in the soil of this arid mining area,but also provides a theoretical basis for subsequent regional research.展开更多
Erratum to:Journal of Earth Science https://doi.org/10.1007/s12583-025-0187-4 The original version of this article unfortunately contained one mistake.The presentation in Page2384 was incorrect.The corrected one is gi...Erratum to:Journal of Earth Science https://doi.org/10.1007/s12583-025-0187-4 The original version of this article unfortunately contained one mistake.The presentation in Page2384 was incorrect.The corrected one is given below.The NTL loss ratio(Figure 4a)was calculated as the variation between pre-earthquake(March 27)and post-earthquake(March 28)radiance values in cloud-free areas.展开更多
INTRODUCTION On March 28,2025,at 06:20:52 UTC,a shallow,magnitude M_(w)7.7 earthquake struck Myanmar(Burma)with an epicenter near the major city of Mandalay.This event,the strongest seismic activity recorded in Myanma...INTRODUCTION On March 28,2025,at 06:20:52 UTC,a shallow,magnitude M_(w)7.7 earthquake struck Myanmar(Burma)with an epicenter near the major city of Mandalay.This event,the strongest seismic activity recorded in Myanmar since 1950,generated intense shaking across much of the country,extended into regions of Thailand,and was felt in China's Yunnan and Guangxi provinces.展开更多
The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect c...The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.展开更多
Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser （K-band） ranging system, the orbital position a...Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser （K-band） ranging system, the orbital position and velocity of a global positioning system （GPS） receiver and non-conservative force of an accelerometer, is established from the perspectives of the power spectrum principle in physics using the semi-analytical approach. Secondly, the accuracy of the global gravitational field is accurately and rapidly estimated based on the combined error model; the cumulative geoid height error is 1.985× 10^-1 m at degree 120 based on GRACE Level 1B measured observation errors of the year 2007 published by the US Jet Propulsion Laboratory （JPL）, and the cumulative geoid height error is 5.825 × 10^-2 m at degree 360 using GRACE Follow-On orbital altitude 250 km and inter-satellite range 50 km. The matching relationship of accuracy indexes from GRACE Follow-On key payloads is brought forward, and the dependability of the combined error model is validated. Finally, the feasibility of high-accuracy and high-resolution global gravitational field estimation from GRACE Follow-On is demonstrated based on different satellite orbital altitudes.展开更多
We apply ambient noise tomography to significant seismic data resources in a region including the northeastern Tibetan plateau, the Ordos block and the Sichuan basin. The seismic data come from about 160 stations of t...We apply ambient noise tomography to significant seismic data resources in a region including the northeastern Tibetan plateau, the Ordos block and the Sichuan basin. The seismic data come from about 160 stations of the provincial broadband digital seismograph networks of China. Ambient noise cross-correlations are performed on the data recorded between 2007 and 2009 and high quality inter-station Rayleigh phase velocity dispersion curves are obtained between periods of 6 s to 35 s. Resulting Rayleigh wave phase velocity maps possess a lateral resolution between 100 km and 200 kin. The phase velocities at short periods （〈20 s） are lower in the Sichuan basin, the northwest segment of the Ordos block and the Weihe graben, and outline sedimentary deposits. At intermediate and long periods （〉25 s）, strong high velocity anomalies are observed within the Ordos block and the Sichuan basin and low phase velocities are imaged in the northeastern Tibetan plateau, reflecting the variation of crustal thickness from the Tibetan plateau to the neighboring regions in the east. Crustal and uppermost mantle shear wave velocities vary strongly between the Tibetan plateau, the Sichuan basin and the Ordos block. The Ordos block and the Sichuan basin are dominated by high shear wave velocities in the crust and uppermost mantle. There is a triangle-shaped low velocity zone located in the northeastern Tibetan plateau, whose width narrows towards the eastern margin of the plateau. No low velocity zone is apparent beneath the Qinling orogen, suggesting that mass may not be able to flow eastward through the boundary between the Ordos block and the Sichuan basin in the crust and uppermost mantle.展开更多
With the 2008 Ms6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches： （1） using the depth phase sPL and （2） using full wavefo...With the 2008 Ms6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches： （1） using the depth phase sPL and （2） using full waveform inversion of local and teleseismic data. We also show that focal depths can be well constrained using the depth phase sPL with single broadband seismic station. Our study indicates that the main shock is located at a depth of ii kin, much shallower than those from other studies, confirming that the earthquake occurs in upper crust. Aftershocks are located in the depth range of 11 16 kin, which is consistent with a ruptured near vertical fault whose width is about 10 km, as expected for an Ms6.1 earthquake.展开更多
In this study, we analyze the regional GPS data of Crustal Movement Observation Network of China （CMONOC） observed from 2009-2013 using the BERNESE GPS software, and then the preliminary results of horizontal veloci...In this study, we analyze the regional GPS data of Crustal Movement Observation Network of China （CMONOC） observed from 2009-2013 using the BERNESE GPS software, and then the preliminary results of horizontal velocity field and strain rate field are presented, which could reflect the overall deformation features in the Chinese mainland from 2009-2013. Besides, the velocity error and the probable factors that could influence the estimate of long-term deformation are also discussed.展开更多
The focal mechanism solutions of the MS. 1 Badong earthquake and subsequent 34 aftershocks at ML 2.0 or more were calculated using the P-wave first motion method; the main earthquake was normal fault dip slip type, an...The focal mechanism solutions of the MS. 1 Badong earthquake and subsequent 34 aftershocks at ML 2.0 or more were calculated using the P-wave first motion method; the main earthquake was normal fault dip slip type, and the slip types of the seismogenic rupture surfaces of the subsequent aftershocks primarily include normal dip slip （14 times）, reverse dip slip （9 times）, normal strike slip （9 times） and reverse strike slip （2 times）. The MS. 1 Badong earthquake activities may be related to the stress adjustment caused by the rise of the groundwater level and the decrease of the frictional resistance between structural planes of rock forma- tions due to the effect of reservoir water penetration, and related to the joint activities of the NE-strike Gaoqiao fault and the near EW-strike Daping fault.展开更多
Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismieity before impoundment and that the epicenters were c...Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismieity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earth- quakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types： Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock （terrane） slip earthquakes, all of which are related to the lithology, structure, and tectonics of near- surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2.0. Therefore, the intensity of the earth- quakes remained at a low level. On November 22, 2008, a magnitude 4.1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-in- duced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.展开更多
Satellite laser ranging （SLR） is one of the major space geodetic instruments, which has various applications in earth science. In this paper, we introduce several issues regarding the key technology implementation o...Satellite laser ranging （SLR） is one of the major space geodetic instruments, which has various applications in earth science. In this paper, we introduce several issues regarding the key technology implementation of high-repetition-rate SLR system. Compared with traditional technology, using kHz and 8ps pulse width laser component, the data quantity and quality of high-repetition-rate satellite laser ranging （SLR） can be significantly improved. The characteristics of high-repetition-rate laser ranging and the key technologies are presented, including the event timer with the precision of picosecond, the generation of range gate signal, and so on. All of them are based on the Field Programmable Gate Arrays （FPGA） and tested on China mobile SLR system-TROS1000. Finally, the observations of satellite Beacon-C are given.展开更多
Based on the nearly diurnal resonance in the tidal gravity observations, the temporal variations in period of the Earth＇s free core nutation （FCN） are investigated by using the tidal gravity observations of 18-year...Based on the nearly diurnal resonance in the tidal gravity observations, the temporal variations in period of the Earth＇s free core nutation （FCN） are investigated by using the tidal gravity observations of 18-year duration recorded continu- ously with a superconducting gravimeter （SG） at Brussels. The effects of the global oceanic tide loading and local barometric pressure on the SG observations have been removed by using eleven high-precision global digital models of oceanic tides and barometric pressure measurements recorded simultaneously at the same site. The results indicate that there exist decade-scale variations in the FCN period. The results should be further confirmed by the measurements using other space-based geodetic techniques （such as the very long baseline interferometry） and the SG observations from globally distributed stations.展开更多
Based on the elastic dislocation theory, multilayered crustal model, and rupture model obtained by seismic waveform inversion, we calculated the coand post-seismic surface deformation and gravity changes caused by the...Based on the elastic dislocation theory, multilayered crustal model, and rupture model obtained by seismic waveform inversion, we calculated the coand post-seismic surface deformation and gravity changes caused by the Yushu M W 6.9 earthquake occurred on April 14, 2010. The observed GPS velocity field and gravity field in Yushu areas are disturbed by the coand post-seismic effects induced by Yushu earthquake, thus the theoretical coand post-seismic deformation and gravity changes will provide important modification for the background tectonic movement of Yushu and surrounding regions. The time relaxation results show that the influences of Yushu earthquake on Yushu and surrounding areas will last as long as 30 to 50 years. The maximum horizontal displacement, vertical uplift and settlement are about 1.96, 0.27 and 0.16 m, respectively, the maximal positive and negative value of gravity changes are 8.892×10-7 m·s-2 and -4.861×10-7 m·s-2 , respectively. Significant spatial variations can be found on the coand post-seismic effects： The co-seismic effect mainly concentrates in the region near the rupture fault, while viscoelastic relaxation mostly acts on the far field. Therefore, when using the geodetic data to research tectonic motion, we should not only consider the effect of co-seismic caused by earthquake, but also pay attention to the effect of viscoelastic relaxation.展开更多
The present-day tectonic activities on the northeastern margin of the Pamir Plateau are mainly E-W oriented extensions, among which the Kongur Extensional System(KES) plays an important role in the internal expansion ...The present-day tectonic activities on the northeastern margin of the Pamir Plateau are mainly E-W oriented extensions, among which the Kongur Extensional System(KES) plays an important role in the internal expansion of the Pamir. As the largest earthquake since Taxkorgan earthquakes in 1895 and 1896, the Aketao earthquake occurred on the Muji fault on the northern portion of the KES in 2016. Since then, the trend of seismic activities along the KES has been paid much attention to. Based on the visco elastic layered lithosphere model, we calculate the co-seismic and post-seismic stress changes caused by five historical earthquakes on the KES and its adjacent areas since 1895, and analyze the interaction among strong earthquakes. The results show that all of the historical earthquakes after 1895 occurred in the areas where the co-seismic and post-seismic Coulomb stress increased. Coulomb stress loading at the hypocenters of the 1896 Taxkorgan earthquake, the 1974 Markansu earthquake and the 2016 Aketao earthquake were 0.251 MPa, 0.013 MPa and 0.563 MPa, respectively. The three earthquakes were catalyzed by such variations. The historical earthquakes increased the stress state on most segments of the Southern Kungai Mountain fault and Kongur fault along the KES. In particular, we can identify 2 visible earthquake gaps with increasing seismic hazard formed on the Qimugan segment and Bulunkou segment of the KES. The Qimugan section and the Bulunkou section are located at the fault transition zone with concentrated stress and high extension rate, so great attention should be paid to their seismic hazard at present day.展开更多
The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary r...The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from - 1 to -0.5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0.71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km^2.展开更多
The Wenchuan Ms8.0 earthquake and the Lushan M7.0 earthquake occurred in the north and south segments of the Longmenshan nappe tectonic belt, respectively. Based on the focal mechanism and finite fault model of the We...The Wenchuan Ms8.0 earthquake and the Lushan M7.0 earthquake occurred in the north and south segments of the Longmenshan nappe tectonic belt, respectively. Based on the focal mechanism and finite fault model of the Wenchuan Ms8.0 earthquake, we calculated the coulomb failure stress change. The inverted coulomb stress changes based on the Nishimura and Chenji models both show that the Lushan MT. 0 earth- quake occurred in the increased area of coulomb failure stress induced by the Wenchuan Ms8. 0 earthquake. The coulomb failure stress increased by approximately 0. 135 - 0. 152 bar in the source of the Lushan M7.0 earthquake, which is far more than the stress triggering threshold. Therefore, the Lushan M7.0 earthquake was most likely triggered by the coulomb failure stress change.展开更多
文摘Geodesy is among the oldest branches of Earth science with historical record of geodesy study by Thales of Miletus more than 2000 years. Originally geodesy was defined as the science of measuring and portraying of the Earth＇s surface, i.e., assuming that the Earth is
基金the support of the China Three Gorges Corporation Science and Technology Fund, with the numbers 0799275the support of the National Natural Science Foundation of China, with the numbers 42174177 and 62106239。
文摘The study area is rich in shale gas resources and has reached the stage of comprehensive development. Shale gas extraction poses risks such as induced seismicity and well closure, compounded by the limited availability of fi xed seismic monitoring stations nearby. To address these challenges, a dense observation array was developed within the study area to monitor and analyze microseismic activity during hydraulic fracturing. Microseismic events generated by hydraulic fracturing typically exhibit low amplitude and signal-to-noise ratio, rendering traditional manual analysis methods impractical. To overcome these limitations, an innovative artifi cial intelligence method combining picking-association-location (PAL) and match-expand- shift-stack (MESS) techniques (PALM) has been utilized for automated seismic detection. Numerous factors influence the accuracy of microseismic detection and localization. To evaluate these factors, the effects of various velocity structure models, instrument types, and station distributions on seismic location were analyzed and compared. The results indicate that the PALM method significantly mitigates the influence of velocity structure models on seismic location accuracy. Additionally, the use of broadband seismic instruments and a uniform station distribution enhances the precision of seismic location results. Furthermore, by integrating data from diff erent types of observation instruments, a comprehensive seismic catalog for the study area was established. These fi ndings not only enhance seismic location accuracy but also provide valuable guidance for optimizing regional seismic monitoring network design and improving seismic risk assessment.
基金the National Natural Science Foundation of China(Grant No.42374105,42204089,42174104)Scientific Research Fund of Institute of Seismology,China Earthquake Administration(Grant No.IS202326341,IS202336350).
文摘On September 5, 2022, an earthquake of magnitude M_(S)6.8 occurred in Luding County, Sichuan Province.This earthquake occurred at the key part of the southeast-clockwise extrusion of material on the eastern margin of the Qinghai Plateau, the Y-shaped confluence of the Xianshuihe, Longmenshan and Anninghe fault zones. In this study, the three-dimensional dynamic crustal density changes in the earthquake area are obtained by the typical gravity change data from 2019 to 2022 before the earthquake and gravity inversion by growing bodies. The results indicate that gravity changes presented an obvious fourquadrant and gradient belt distribution in the Luding area before the earthquake. The threedimensional density horizontal slices show that small density changes occurred at the epicenter in the mid-to-upper crust between 2019.9-2020.9 and 2019.9-2021.9. At the same time, the surrounding areas exhibited a positive and negative quadrant distribution. These observations indicate that the source region was likely in a stable locked state, with locking-in shear forces oriented in the NW and NE directions. From 2021.9 to 2022.8, the epicentral region showed negative density changes, indicating that the source region was in the expansion stage, approaching a near-seismic state. The three-dimensional density vertical slices reveal a southeastward migration of positive and negative densities near the epicenter and on the western of the Xianshuihe Fault Zone, indicating that the material is flowing out to the southeast. The observed local negative density changes at the epicenter along the Longmenshan Fault Zone are likely associated with the NE-oriented extensional stress shown by the seismic source mechanism. The above results can provide a basis for interpreting pre-earthquake gravity and density changes,thereby contributing to the advancement of earthquake precursor theory.
基金supported by the Third Xinjiang Scientific Expedition Project(2021XJKK1104),i.e.,the Investigation and Assessment of the Effects of Energy and Mineral Resource Development in Turpan Basin on Regional Ecological Environment。
文摘Coal mining predisposes soils to heavy metal(HM)accumulation,which adversely affects the ecological environment and human health,particularly in extremely arid and vulnerable areas.In this study,soil samples were gathered from the Black Mountain Open Pit Coal Mine in Turpan City,Northwest China to determine the health risk of heavy metals(HMs).Results showed that positive matrix factorization model divided the sources of soil HMs into four categories,i.e.,natural and animal husbandry(43.46%),industrial transportation(22.87%),fossil fuel combustion(10.64%),and atmospheric deposition and domestic pollution(23.03%).All kinds of pollution evaluation indices showed that Cd(cadmium)and Pb(plumbum)pollution was evident.The Monte Carlo simulated health risk assessment results showed that 4.00%non-carcinogenic risk and 12.00%carcinogenic risk were posed to children,and the positive matrix factorization-based health risk assessment showed that fossil fuel combustion had the highest contribution to the health risks to adults and children,while industrial transportation was the lowest.In this study,the risks of HMs in the soil of mining area were analyzed using source analysis,which not only provides reliable data support for the prevention and control of HM pollution in the soil of this arid mining area,but also provides a theoretical basis for subsequent regional research.
文摘Erratum to:Journal of Earth Science https://doi.org/10.1007/s12583-025-0187-4 The original version of this article unfortunately contained one mistake.The presentation in Page2384 was incorrect.The corrected one is given below.The NTL loss ratio(Figure 4a)was calculated as the variation between pre-earthquake(March 27)and post-earthquake(March 28)radiance values in cloud-free areas.
基金supported by the National Key R&D Program of the Republic of China(Nos.2023YFC3007303,2017YFB0504104)the Science and Technology Projects of Gansu Provincial(No.24JRRA1188)。
文摘INTRODUCTION On March 28,2025,at 06:20:52 UTC,a shallow,magnitude M_(w)7.7 earthquake struck Myanmar(Burma)with an epicenter near the major city of Mandalay.This event,the strongest seismic activity recorded in Myanmar since 1950,generated intense shaking across much of the country,extended into regions of Thailand,and was felt in China's Yunnan and Guangxi provinces.
基金supported by the Institute of Seismology Foundation, China Earthquake Administration (201326126)
文摘The research about subsurface characteristics by using transient electromagnetic method（TEM） and high density resistivity method（HDRM） were already conducted in Ordos. The objective of this research is to detect coalmine goaf areas based on rock resistivity. The data processing using wavelet transform, three point smoothing, RES2 DINV and Maxwell processing software to obtain 2D resistivity structure. The results showed that the layers with maximum resistivity values（30e33 U m on Line 1, 30e31 U m on Line 2, 32e40 U m on Line3） are founded at station 1e7, and 14e20 on Line 1,13e18 on Line 2, and 8e13 and 16e20 on Line 3 which is predicted as goaf layer, and the minimum resistivity values（20e26 U m of TEM, 45e75 U m of HDRM） at the other layers. This resistivity difference was caused by the geology and characteristics of the study area which is located close by the cleugh with rich coal, so the goaf area distinguishable with aquifer layer and coal seam. The results were also significant accidents and serious destruction of ecological environment.
基金supported by the National Natural Science Foundation of China (Grant No 40674038)the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (Grant Nos KZCX2-YW-143 and KZCX2-YW-202)+1 种基金the National High Technology Research and Development Program of China (863) (Grant Nos 2009AA12Z138 and 2006AA09Z153)the Grant-in-Aid for Scientific Research of Japan (Grant No B19340129)
文摘Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser （K-band） ranging system, the orbital position and velocity of a global positioning system （GPS） receiver and non-conservative force of an accelerometer, is established from the perspectives of the power spectrum principle in physics using the semi-analytical approach. Secondly, the accuracy of the global gravitational field is accurately and rapidly estimated based on the combined error model; the cumulative geoid height error is 1.985× 10^-1 m at degree 120 based on GRACE Level 1B measured observation errors of the year 2007 published by the US Jet Propulsion Laboratory （JPL）, and the cumulative geoid height error is 5.825 × 10^-2 m at degree 360 using GRACE Follow-On orbital altitude 250 km and inter-satellite range 50 km. The matching relationship of accuracy indexes from GRACE Follow-On key payloads is brought forward, and the dependability of the combined error model is validated. Finally, the feasibility of high-accuracy and high-resolution global gravitational field estimation from GRACE Follow-On is demonstrated based on different satellite orbital altitudes.
基金supported by Chinese Academy of Sciences grant kzcx2-yw-142 and Y009021002National Natural Science Foundation of China under grant No. 40974034+1 种基金NSF-EAR award 0944022NSF-OISE 0730154 at the University of Colorado at Boulder
文摘We apply ambient noise tomography to significant seismic data resources in a region including the northeastern Tibetan plateau, the Ordos block and the Sichuan basin. The seismic data come from about 160 stations of the provincial broadband digital seismograph networks of China. Ambient noise cross-correlations are performed on the data recorded between 2007 and 2009 and high quality inter-station Rayleigh phase velocity dispersion curves are obtained between periods of 6 s to 35 s. Resulting Rayleigh wave phase velocity maps possess a lateral resolution between 100 km and 200 kin. The phase velocities at short periods （〈20 s） are lower in the Sichuan basin, the northwest segment of the Ordos block and the Weihe graben, and outline sedimentary deposits. At intermediate and long periods （〉25 s）, strong high velocity anomalies are observed within the Ordos block and the Sichuan basin and low phase velocities are imaged in the northeastern Tibetan plateau, reflecting the variation of crustal thickness from the Tibetan plateau to the neighboring regions in the east. Crustal and uppermost mantle shear wave velocities vary strongly between the Tibetan plateau, the Sichuan basin and the Ordos block. The Ordos block and the Sichuan basin are dominated by high shear wave velocities in the crust and uppermost mantle. There is a triangle-shaped low velocity zone located in the northeastern Tibetan plateau, whose width narrows towards the eastern margin of the plateau. No low velocity zone is apparent beneath the Qinling orogen, suggesting that mass may not be able to flow eastward through the boundary between the Ordos block and the Sichuan basin in the crust and uppermost mantle.
基金financial supported by Joint Seismological Science Foundation of China (No.200808078)National Natural Science Foundation of China (Nos.40821160549 and 41074032)
文摘With the 2008 Ms6.1 Panzhihua earthquake as a case study, we demonstrate that the focal depth of the main shock can be well constrained with two approaches： （1） using the depth phase sPL and （2） using full waveform inversion of local and teleseismic data. We also show that focal depths can be well constrained using the depth phase sPL with single broadband seismic station. Our study indicates that the main shock is located at a depth of ii kin, much shallower than those from other studies, confirming that the earthquake occurs in upper crust. Aftershocks are located in the depth range of 11 16 kin, which is consistent with a ruptured near vertical fault whose width is about 10 km, as expected for an Ms6.1 earthquake.
基金supported by Foundation of Institute of Seismology,China Earthquake Administration(201326119)the National Natural Science Foundation of China(41074016,41274027,41304067)
文摘In this study, we analyze the regional GPS data of Crustal Movement Observation Network of China （CMONOC） observed from 2009-2013 using the BERNESE GPS software, and then the preliminary results of horizontal velocity field and strain rate field are presented, which could reflect the overall deformation features in the Chinese mainland from 2009-2013. Besides, the velocity error and the probable factors that could influence the estimate of long-term deformation are also discussed.
基金supported by the Director Foundation of the Institute of Seismology,China Earthquake Adminstration(IS201246114)the Special Fund of China Three Gorges Corporation(SXSN/3354)
文摘The focal mechanism solutions of the MS. 1 Badong earthquake and subsequent 34 aftershocks at ML 2.0 or more were calculated using the P-wave first motion method; the main earthquake was normal fault dip slip type, and the slip types of the seismogenic rupture surfaces of the subsequent aftershocks primarily include normal dip slip （14 times）, reverse dip slip （9 times）, normal strike slip （9 times） and reverse strike slip （2 times）. The MS. 1 Badong earthquake activities may be related to the stress adjustment caused by the rise of the groundwater level and the decrease of the frictional resistance between structural planes of rock forma- tions due to the effect of reservoir water penetration, and related to the joint activities of the NE-strike Gaoqiao fault and the near EW-strike Daping fault.
基金supported by the China Three Gorges Corporation(SXSN/2377)
文摘Seismic monitoring data for the past 50 years in the Three Gorges Reservoir area show that the reservoir head area is a typical weak seismic region with low seismieity before impoundment and that the epicenters were concentrated in the east and west sides of the Zigui Basin, most of which were natural tectonic earth- quakes. After impoundment, the seismic activity shifted to the segment between Badong and Zigui along the Yangtze River, mainly within 5 km of the reservoir bank. The seismogenesis was categorized into four types： Karst collapse earthquakes, earthquakes caused by Karst gas explosion, mining tunnel collapse earthquakes, and rock （terrane） slip earthquakes, all of which are related to the lithology, structure, and tectonics of near- surface geological bodies of the area. Compared with the seismicity before impoundment, the seismic frequency increase was remarkable, with most of the magnitudes below Ms2.0. Therefore, the intensity of the earth- quakes remained at a low level. On November 22, 2008, a magnitude 4.1 earthquake, the largest earthquake recorded since impoundment, occurred in Quyuan Town, Zigui County. The intensity and PGA of reservoir-in- duced earthquakes are higher than those of tectonic earthquakes with equal magnitude, but the peak intensity of reservoir-induced earthquakes is not likely to go beyond that of the estimated range from earlier studies.
基金supported by the National Natural Science Foundation of China(40774013)
文摘Satellite laser ranging （SLR） is one of the major space geodetic instruments, which has various applications in earth science. In this paper, we introduce several issues regarding the key technology implementation of high-repetition-rate SLR system. Compared with traditional technology, using kHz and 8ps pulse width laser component, the data quantity and quality of high-repetition-rate satellite laser ranging （SLR） can be significantly improved. The characteristics of high-repetition-rate laser ranging and the key technologies are presented, including the event timer with the precision of picosecond, the generation of range gate signal, and so on. All of them are based on the Field Programmable Gate Arrays （FPGA） and tested on China mobile SLR system-TROS1000. Finally, the observations of satellite Beacon-C are given.
基金supported by the Key Project of the Knowledge Innovation of Chinese Academy of Sciences (Grant No. KZCX2-YW-133, KZCX2-YW-Q08-2)National Natural Science Foun-dation of China (Grant No. 40874038 and 40730316)
文摘Based on the nearly diurnal resonance in the tidal gravity observations, the temporal variations in period of the Earth＇s free core nutation （FCN） are investigated by using the tidal gravity observations of 18-year duration recorded continu- ously with a superconducting gravimeter （SG） at Brussels. The effects of the global oceanic tide loading and local barometric pressure on the SG observations have been removed by using eleven high-precision global digital models of oceanic tides and barometric pressure measurements recorded simultaneously at the same site. The results indicate that there exist decade-scale variations in the FCN period. The results should be further confirmed by the measurements using other space-based geodetic techniques （such as the very long baseline interferometry） and the SG observations from globally distributed stations.
基金supported by Chinese Academy of Sciences (Nos.KZCX2-YW-116 and KZCX2-YW-142)National Natural Science Foundation of China (No. 40974034)
文摘Based on the elastic dislocation theory, multilayered crustal model, and rupture model obtained by seismic waveform inversion, we calculated the coand post-seismic surface deformation and gravity changes caused by the Yushu M W 6.9 earthquake occurred on April 14, 2010. The observed GPS velocity field and gravity field in Yushu areas are disturbed by the coand post-seismic effects induced by Yushu earthquake, thus the theoretical coand post-seismic deformation and gravity changes will provide important modification for the background tectonic movement of Yushu and surrounding regions. The time relaxation results show that the influences of Yushu earthquake on Yushu and surrounding areas will last as long as 30 to 50 years. The maximum horizontal displacement, vertical uplift and settlement are about 1.96, 0.27 and 0.16 m, respectively, the maximal positive and negative value of gravity changes are 8.892×10-7 m·s-2 and -4.861×10-7 m·s-2 , respectively. Significant spatial variations can be found on the coand post-seismic effects： The co-seismic effect mainly concentrates in the region near the rupture fault, while viscoelastic relaxation mostly acts on the far field. Therefore, when using the geodetic data to research tectonic motion, we should not only consider the effect of co-seismic caused by earthquake, but also pay attention to the effect of viscoelastic relaxation.
基金funded by the Spark Program of Earthquake Technology of CEA(XH17023Y)The National Natural Science Foundation of China(41604079,41504011,41574017,41541029)the Science and Technology Partnership Program of Shanghai Cooperation Organization(2017E01030)
文摘The present-day tectonic activities on the northeastern margin of the Pamir Plateau are mainly E-W oriented extensions, among which the Kongur Extensional System(KES) plays an important role in the internal expansion of the Pamir. As the largest earthquake since Taxkorgan earthquakes in 1895 and 1896, the Aketao earthquake occurred on the Muji fault on the northern portion of the KES in 2016. Since then, the trend of seismic activities along the KES has been paid much attention to. Based on the visco elastic layered lithosphere model, we calculate the co-seismic and post-seismic stress changes caused by five historical earthquakes on the KES and its adjacent areas since 1895, and analyze the interaction among strong earthquakes. The results show that all of the historical earthquakes after 1895 occurred in the areas where the co-seismic and post-seismic Coulomb stress increased. Coulomb stress loading at the hypocenters of the 1896 Taxkorgan earthquake, the 1974 Markansu earthquake and the 2016 Aketao earthquake were 0.251 MPa, 0.013 MPa and 0.563 MPa, respectively. The three earthquakes were catalyzed by such variations. The historical earthquakes increased the stress state on most segments of the Southern Kungai Mountain fault and Kongur fault along the KES. In particular, we can identify 2 visible earthquake gaps with increasing seismic hazard formed on the Qimugan segment and Bulunkou segment of the KES. The Qimugan section and the Bulunkou section are located at the fault transition zone with concentrated stress and high extension rate, so great attention should be paid to their seismic hazard at present day.
基金supported by the Director Foundation of the Institute of Seismology,China Earthquake Administration(201056076,201116002)
文摘The seismic intensities, lithologic characteristics and terrain features from a 3000 km2-region near the epicenter of the Lushan earthquake are used to analyze earthquake-induced geological disaster. The preliminary results indicate that secondary effects of the earthquake will affect specific areas, including those with glutenite and carbonate bedrock, a seismic intensity of IX, slopes between 40° and 50°, elevations of less than 2500 m, slope change rates between 20° and 30°, slope curvatures from - 1 to -0.5 and 0. 5 to 1, and relief between 50 and 100 m. Regions with susceptibility indices greater than 0.71 are prone to landslides and collapses. The secondary features are mainly distributed on both sides of the ridges that extend from Baosheng to Shuangshi and from Baosheng to Longxing. Other features are scattered on both sides of the ridges that extend from Qishuping to Baosheng and from Masangping to Lingguan. The distribution of the earthquake-related features trends in the NE direction, and the area that was most affected by the Lushan earthquake covers approximately 52.4 km^2.
基金supported by the Director Foundation of Institute of SeismologyChina Earthquake Administration(201056088)
文摘The Wenchuan Ms8.0 earthquake and the Lushan M7.0 earthquake occurred in the north and south segments of the Longmenshan nappe tectonic belt, respectively. Based on the focal mechanism and finite fault model of the Wenchuan Ms8.0 earthquake, we calculated the coulomb failure stress change. The inverted coulomb stress changes based on the Nishimura and Chenji models both show that the Lushan MT. 0 earth- quake occurred in the increased area of coulomb failure stress induced by the Wenchuan Ms8. 0 earthquake. The coulomb failure stress increased by approximately 0. 135 - 0. 152 bar in the source of the Lushan M7.0 earthquake, which is far more than the stress triggering threshold. Therefore, the Lushan M7.0 earthquake was most likely triggered by the coulomb failure stress change.
